System, method, and computer-readable medium for abbreviated-code dialing in a network system

ABSTRACT

A system, method, and computer readable medium for abbreviated dialing in a femtocell network is provided. A user having authorized access to the femtocell network may dial another authorized user using an abbreviated code. On receipt of the call request, a femtocell system may evaluate the destination number to determine if it is an abbreviated code. If the dialed number is not an abbreviated code, the femtocell system may direct the call request to the telecommunication core network for processing thereby. If the dialed number is evaluated by the femtocell system as an abbreviated code, the femtocell system may direct the call request to an on-site PBX for call handling. If the abbreviated code is a valid code and the dialed user equipment is currently in the femtocell network service area, the PBX may then complete the call setup within the femtocell network.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/734,434 entitled SYSTEM, METHOD, AND COMPUTER-READABLE MEDIUM FORABBREVIATED-CODE DIALING IN A NETWORK SYSTEM, filed on Jun. 9, 2015, nowissued U.S. Pat. No. 9,565,303, issued on Feb. 7, 2017, which is acontinuation of U.S. patent application Ser. No. 13/729,895 entitledSYSTEM, METHOD, AND COMPUTER-READABLE MEDIUM FOR ABBREVIATED-CODEDIALING IN A NETWORK SYSTEM, filed on Dec. 28, 2012, now issued U.S.Pat. No. 9,055,581 issued on Jun. 9, 2015, which is a continuation ofU.S. patent application Ser. No. 12/252,226 entitled SYSTEM, METHOD, ANDCOMPUTER-READABLE MEDIUM FOR ABBREVIATED-CODE DIALING IN A NETWORKSYSTEM, filed on Oct. 15, 2008, now issued U.S. Pat. No. 8,346,216,issued on Jan. 1, 2013, which in turn claim priority to U.S. provisionalpatent application Ser. No. 61/003,151 entitled SIP-IOS ADAPTER FUNCTIONfiled Nov. 15, 2007, the disclosure of each of which are incorporated intheir entirety herein by reference.

FIELD OF THE INVENTION

The present invention is generally related to radio access technologiesand, more particularly, to mechanisms for abbreviated dialing in anetwork system.

BACKGROUND OF THE INVENTION

Contemporary cellular radio systems, or mobile telecommunicationsystems, provide an over-the-air interface to wireless user equipments(UEs) via a radio access network (RAN) that interfaces with at least onecore network. The RAN may be implemented as, for example, a CDMA2000RAN, a Universal Mobile Telecommunications System (UMTS) RAN, a GlobalSystem for Mobile communications (GSM) RAN, or another suitable radioaccess network implementation. A UE may comprise, for example, a mobileterminal such as a mobile telephone, a laptop computer featuring mobiletelephony software and hardware, a personal digital assistant (PDA), orother suitable equipment adapted to transfer and receive voice or datacommunications with the radio access network.

A RAN covers a geographical area comprised of any number of cells eachcomprising a relatively small geographic area of radio coverage. Eachcell is provisioned by a cell site that includes a radio tower, e.g., abase transceiver station (BTS), and associated equipment. BTSscommunicate with UEs over an air interface within radio range of theBTSs.

Numerous BTSs in the RAN may be communicatively coupled to a basestation controller, also commonly referred to as a radio networkcontroller (RNC). The BSC manages and monitors various system activitiesof the BTSs serviced thereby. BSCs are coupled with at least one corenetwork.

BTSs are typically deployed by a carrier network in areas having a highpopulation density. The traffic capacity of a cell site is limited bythe site's capacity and affects the spacing of cell sites. In suburbanareas, sites are often up to two miles apart, while cell sites deployedin dense urban areas may be as close as one-quarter of a mile apart.Because the traffic capacity of a cell site is finitely limited, as isthe available frequency spectrum, mobile operators have a vestedinterest in technologies that allow for increased subscriber capacity.

A microcell site comprises a cell in a mobile phone network that coversa limited geographic area, such as a shopping center, hotel, airport, orother infrastructure that may have a high density mobile phone usage. Amicrocell typically uses power control to limit the radius of themicrocell coverage. Typically a microcell is less than a mile wide.

Although microcells are effective for adding network capacity in areaswith high mobile telephone usage, microcells extensively rely on theRAN, e.g., a controlling BSC and other carrier functions. Becausecontemporary BSCs have limited processing and interface capacity, thenumber of BTSs—whether microcell BTSs or typical carrier BTSs—able to besupported by the BSC or other RAN functions is disadvantageouslylimited.

Contemporary interest exists in providing enterprise and office access,including small office/home office (SOHO) radio access, by an evensmaller scale BTS. The radio coverage area of such a system is typicallyreferred to as a femtocell. In a system featuring a femtocell, a UE maybe authorized to operate in the femtocell when proximate the femtocellsystem, e.g., while the UE is located in the SOHO. When the UE movesbeyond the coverage area of the femtocell, the UE may then be servicedby the carrier network. The advantages of deployment of femtocells arenumerous. For instance, mobile users frequently spend large amounts oftime located at, for example, home, and many such users rely extensivelyon cellular network service for telecommunication services during thesetimes. For example, a recent survey indicated that nearly thirteenpercent of U.S. cell phone customers do not have a landline telephoneand rely solely on cell phones for receiving telephone service. From acarrier perspective, it would be advantageous to have telephone servicesprovisioned over a femtocell system, e.g., deployed in the user's home,to thereby reduce the load, and effectively increase the capacity, onthe carrier RAN infrastructure. However, various issues related toprovisioning of exchange services in a femtocell network remainunresolved.

Therefore, what is needed is a mechanism that overcomes the describedproblems and limitations.

SUMMARY OF THE INVENTION

The present invention provides a system, method, and computer readablemedium for call processing in a network system. A communication systemfeatures an IP-based femtocell system for provisioning communicationservices to a user equipment. Abbreviated dialing is supported by thefemtocell network operating in conjunction with an on-site PBX or a SIPswitch. A user having authorized access to the femtocell network maydial another authorized user using an abbreviated code, e.g., a 4-digitcode comprising the 4-digit station number. On receipt of the callrequest, the femtocell system may evaluate the destination number todetermine if it is an abbreviated code. If the dialed number is not anabbreviated code, the femtocell system may direct the call request tothe telecommunication core network for processing thereby. If the dialednumber is evaluated by the femtocell system as an abbreviated code, thefemtocell system may direct the call request to the PBX or SIP switchfor call handling. In this instance, the PBX or SIP switch may determineif the abbreviated code is a valid code, i.e., if it is assigned to anauthorized UE. If so, the PBX or SIP switch may then determine if thedialed UE is currently in the femtocell network service area. In theevent the dialed UE is in the femtocell network service area, the PBX orSIP switch may then complete the call setup within the femtocellnetwork. If the PBX or SIP switch determines that the dialed UE is notcurrently in the femtocell network service area, the PBX or SIP switchmay direct the call request to the telecommunication core network forprocessing of the call setup.

In one embodiment of the disclosure, a method of call processing in anetwork system is provided. The method includes receiving, by afemtocell system, a call setup request from a first user equipment,performing an evaluation of a destination number of a second userequipment to which the call is directed, and determining, based onresults of the evaluation, the call setup request is to be directed toone of a private branch exchange deployed in a femtocell network and atelecommunication core network communicatively coupled with thefemtocell network.

In a further embodiment of the disclosure, a computer-readable mediumhaving computer-executable instructions for execution by a processingsystem, the computer-executable instructions for call processing in anetwork system is provided. The computer-readable medium comprisesinstructions that receive, by a femtocell system, a call setup requestfrom a first user equipment, perform an evaluation of a destinationnumber of a second user equipment to which the call is directed, whereinthe evaluation determines if the destination number comprises anabbreviated code, and determine, based on results of the evaluation, thecall setup request is to be directed to one of a private branch exchangedeployed in a femtocell network and a telecommunication core networkcommunicatively coupled with the femtocell network.

In a further embodiment of the disclosure, a system configured for callprocessing in a network system is provided. The system includes apacket-switched network, an IP Multimedia subsystem communicativelycoupled with the packet-switched network, and a femtocell networkcommunicatively coupled with the packet-switched network that includes aprivate branch exchange that maintains a data structure that associatesdirectory numbers of authorized user equipments with abbreviated codes.The femtocell network includes a femtocell system that receives a callsetup request from a first user equipment, performs an evaluation todetermine whether a destination number of a second user equipment towhich the call setup request is directed comprises an abbreviated code,and determines, based on results of the evaluation, the call setuprequest is to be directed to one of the private branch exchange and theIP Multimedia subsystem.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures, in which:

FIG. 1 is a diagrammatic representation of a network system thatincludes a cellular network adapted to provide macro-cellular coverage;

FIG. 2 is a diagrammatic representation of a conventional network systemconfiguration featuring a femtocell;

FIG. 3 is a diagrammatic representation of a network system in which afemtocell system implemented in accordance with an embodiment of thepresent invention may be deployed;

FIG. 4A is a simplified diagrammatic representation of the femtocellsystem depicted in FIG. 3 that may be connected with an IP backhaul inaccordance with an embodiment;

FIG. 4B is a simplified diagrammatic representation of an alternativeembodiment of a femtocell system that may be connected with an IPbackhaul;

FIG. 5 is a diagrammatic representation of an exemplary sessioninitiation protocol registration message generated by a femtocell systemon behalf of a user equipment in accordance with an embodiment;

FIG. 6 is a diagrammatic representation of a network system featuring afemtocell network implemented in accordance with an embodiment;

FIG. 7 is a diagrammatic representation of an exemplary softwareconfiguration of a user equipment adapted for engaging in communicationswith femtocell systems in accordance with an embodiment;

FIG. 8 is a diagrammatic representation of a PBX data structure thatfacilitates abbreviated code dialing within a femtocell network inaccordance with an embodiment;

FIG. 9 is a flowchart that depicts a femtocell call processing routineimplemented in accordance with an embodiment; and

FIG. 10 is a flowchart that depicts a PBX call processing routineimplemented in accordance with an embodiment

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that the following disclosure provides manydifferent embodiments or examples for implementing different features ofvarious embodiments. Specific examples of components and arrangementsare described below to simplify the present disclosure. These are, ofcourse, merely examples and are not intended to be limiting.

FIG. 1 is a diagrammatic representation of a network system 100 thatincludes a cellular network 110 adapted to provide macro-cellularcoverage to a user equipment. Cellular network 110 may comprise, forexample, a code-division multiple access (CDMA) network, such as aCDMA-2000 network.

Cellular network 110 may include any number of base transceiver stations(BTSs) 112 a-112 c communicatively coupled with a base stationcontroller (BSC) 114 or RNC. Each individual BTS 112 a-112 c under thecontrol of a given BSC may define a radio cell operating on a set ofradio channels thereby providing service to a user equipment (UE) 125,such as a mobile terminal. BSC 114 manages the allocation of radiochannels, receives measurements from mobile terminals, controlshandovers, as well as various other functions as is understood. BSC 114is interconnected with a mobile services switching center (MSC) 116 thatprovides mobile terminal exchange services. BSC 114 may be additionallycoupled with a packet data serving node (PDSN) 118 or other gatewayservice that provides a connection point between the CDMA radio accessnetwork and a packet network, such as Internet 160, and providesmobility management functions and packet routing services. MSC 116 maycommunicatively interface with a circuit switched network, such as thepublic switched telephone network (PSTN) 150, and may additionally becommunicatively coupled with an interworking function (IWF) 122 thatprovides an interface between cellular network 110 and PSTN 150.

System 100 may also include a signaling system, such as a signalingsystem #7 (SS7) network 170. SS7 network 170 provides a set of telephonysignaling protocols which are used to set up the vast majority of theworld's PSTN telephone calls. SS7 network 170 is also used in cellularnetworks for circuit switched voice and packet-switched dataapplications. As is understood, SS7 network 170 includes varioussignaling nodes, such as any number of service control points (SCPs)172, signal transfer points (STPs) 174, and service switching points(SSPs) 176.

BTSs 112 a-112 c deployed in cellular network 110 may service numerousnetwork 110 subscribers. Cell cites provided by BTSs 112 a-112 ccommonly feature site ranges of a quarter to a half mile, e.g., indensely populated urban areas, to one to two miles in suburban areas. Inother remotely populated regions with suitable geography, site rangesmay span tens of miles and may be effectively limited in size by thelimited transmission distance of relatively low-powered UEs. As referredto herein, a cell provided by a BTS deployed in carrier network 110 foraccess by any authorized network 110 subscriber is referred to as amacrocell.

FIG. 2 is a diagrammatic representation of a conventional network system200 configuration featuring a femtocell. In the depicted example, acentral BSC 214 deployed in a cellular carrier network 210 may connectwith a soft switch core 212 that is connected with a MSC 216. MSC 216connects with the cellular core network and may interface with othernetworks, such as the PSTN as is understood. BSC 214 may be connectedwith and service numerous BTSs 212 a-212 c that provide macrocells tocellular network 210 subscribers.

BSC 214 may additionally connect with a tunnel gateway system 218 thatis adapted to establish secured tunnels 232 a-232 x with respectivefemtocell systems 250 a-250 x. Femtocells comprise cellular accesspoints that connect to a mobile operator's network using, for example, aresidential DSL or cable broadband connection. Femtocells 250 a-250 xprovide a radio access point for UE 225 when the UE is within range of afemtocell system with which the UE has authorized access. For example,femtocell system 250 a may be deployed in a residence of the user of UE225. Accordingly, when the user is within the residence, mobiletelecommunications may be provided to UE 225 via an air-interfaceprovided by femtocell system 250 a. In this instance, UE 225 iseffectively offloaded from the macro BTS, e.g., BTS 212 a, andcommunications to and from the UE are carried out with femtocell system250 a over Internet 260. Thus, femtocell systems 250 a-250 x may reducethe radio resource demands by offloading UEs from macrocells tofemtocells and thereby provide for increased subscriber capacity ofcellular network 210.

In contemporary implementations such as that depicted in FIG. 2, afemtocell system 250 a comprises a transceiver without intelligence andis thus required to be connected and managed by BSC 214. Thus, femtocellsystems 250 a-250 x are reliant on the carrier network centralized BSC214 which has limited capacity and thus does not exhibit desirablescaling characteristics or capabilities. Moreover, high communicationsoverhead are realized by the BTS backhaul.

FIG. 3 is a diagrammatic representation of a network system 300 in whicha femtocell system implemented in accordance with an embodiment of theinvention may be deployed. System 300 includes a radio access network(RAN) 310 that provides an over-the-air interface with a UE 325, e.g., amobile terminal. RAN 310 may comprise, for example, a CDMA radio accessnetwork or another suitable RAN. RAN 310 may comprise various BTSs andassociated base station controllers BSCs as well as other infrastructureas is understood. UE 325 may be implemented as a personal digitalassistant (PDA), a mobile phone, a computer, or another device adaptedto interface with RAN 310.

System 300 may include an IP Multimedia Subsystem (IMS) 320 architectureadapted to provide IP service to UE 325. To this end, RAN 310 iscommunicatively coupled with a serving general packet radio service(GPRS) support node (SGSN) 314 and a gateway GPRS support node (GGSN)316. SGSN 314 provides the delivery of data packets from and to UE 325within its service area. GGSN 316 provides an interface between the GPRSbackbone network and external packet data networks. GGSN 316 iscommunicatively coupled with a policy decision function (PDF) 318 thatprovides authorization of media plane resources, e.g., quality ofservice (QoS) authorizations, policy control, bandwidth management, andthe like. PDF 318 may be communicatively coupled with a call sessioncontrol function (CSCF) 320.

CSCF 320 comprises various session initiation protocol (SIP) servers orproxies that process SIP signaling packets in IMS 320. CSCF 320 mayinclude a proxy-CSCF (P-CSCF) that provides a first point of contact foran IMS-compliant UE. The P-CSCF may be located in the visited network,or in the UE's home network if the visited network is not fullyIMS-compliant. UE 325 may discover the P-CSCF, e.g., by using DynamicHost Configuration Protocol (DHCP), or by assignment in a packet dataprotocol (PDP) context. CSCF 320 additionally includes a Serving-CSCF(S-CSCF) that comprises the central node of the signaling plane. TheS-CSCF comprises a SIP server, but additionally performs sessioncontrol. The S-CSCF is located in the home network and interfaces with ahome subscriber server (HSS) 340 to download and upload user profiles.CSCF 320 further includes an Interrogating-CSCF (I-CSCF) that comprisesa SIP function located at the edge of an administrative domain. TheI-CSCF has an IP address that is published in the Domain Name System(DNS) 372 that facilitates location of the I-CSCF by remote servers.Thus, the I-CSCF is used as a forwarding point for receipt of SIPpackets within the domain. CSCF 320 may interface with an IP switch,such as a SIP switch 380. SIP switch 380 includes a Registrar 382 thatprocesses register requests and provides location and contactinformation to a location server 384.

HSS 340 comprises a user database that supports the IMS network entitiesthat manage calls. HSS 340 stores user profiles that specifysubscription-related information of authorized users, authenticates andauthorizes users, and provides information about the user's physicallocation. Various application servers (AS) 342 a-342 n that host andexecute services interface with CSCF 320 via SIP.

CSCF 320 is coupled with a breakout gateway control function (BGCF) 322that comprises a SIP server that provides routing functionality based ontelephone numbers. BGCF 322 is used when a UE places a call from the IMSto a phone in a circuit switched network, e.g., PSTN 330, or the publicland mobile network. A media gateway controller Function (MGCF) 324performs call control protocol conversion between SIP and ISDN User Part(ISUP) and interfaces with a signaling gateway (SGW) 326. SGW 326interfaces with the signaling plane of a circuit switched network, e.g.,PSTN 330. SGW 326 may transform lower layer protocols, such as StreamControl Transmission Protocol (SCTP), into the Message Transfer Part(MTP) protocol, and pass ISUP data from MGCF 324 to PSTN 330 or anothercircuit switched network. A media gateway (MGW) 328 interfaces with themedia plane of PSTN 330 or another circuit switched network byconverting data between real-time transport protocol (RTP) and pulsecode modulation (PCM), and may also be employed for transcoding when thecodecs of the IMS and circuit switched networks differ. Resources of MGW328 are controlled by MGCF 324. Fixed access, e.g., IP telephony devices374 a-374 b, may connect with IMS network via Internet 370 that iscommunicatively coupled with IMS network 320 by way of border gateway360.

As is understood, DNS 372 comprises a scalable namespace thatfacilitates access to entities deployed on the Internet or privatenetworks. DNS 372 maintains various records for host names, servers, andthe like. For example, DNS 372 maintains records (commonly referred toas “A records”) that map hostnames to IP addresses, pointer (PTR)records that map IP addresses to canonical names to facilitate reverseDNS lookups, service (SRV) records that specify information on availableservices, naming authority pointer (NAPTR) records that facilitateregular expression based rewriting, and various other records. DNS 372may additionally include a telephone number mapping (ENUM) system thatfacilitates resolution of SIP addresses from E.164 number as isunderstood.

A base station manager (BSM) 378 may be deployed in Internet 370 and maybe adapted to communicate with numerous femtocell systems and femtocellnetworks. BSM 378 may provide various operations, maintenance, andmanagement functions to femtocell systems. For example, BSM 378 mayprovide service provisioning of femtocell systems, e.g., by providingconfiguration downloads to femtocell systems and preloading defaultconfiguration data for femtocell systems distributed via sales channels.BSM 378 may provide various support and maintenance features, such asalarm and periodic statistics reporting, automatic remote software imagedistribution to femtocell systems, provide upgrades andreconfigurations, and may provide remote access via Internet 370 fordiagnostics and customer support.

In accordance with an embodiment, a femtocell system 350 may includeintegrated BTS and BSC functions and may feature additional capabilitiesavailable in the provided femtocell site coverage area. Femtocell system350 provides an IP-accessible radio access network, is adapted foroperation with IMS 320, and provides radio link control functions.Femtocell system 350 may be communicatively coupled with Internet 370via any variety of backhaul technologies, such as an 802.11x link, a10/100 BaseT LAN link, a T1/E1 Span or fiber, cable set top box, DSLmodem connected with a central office digital subscriber line accessmultiplexer, a very small aperture terminal (VSAT), or another suitablebackhaul infrastructure.

Femtocell system 350 may include a session initiation protocol (SIP)adapter that supports a SIP client pool and provides conversion of callset-up functions to SIP client set-up functions. For example, a SIPclient pool allocated by femtocell system 350 may comprise a pluralityof SIP user agents 352 a-352 c that each may be allocated for a UEauthorized to access femtocell system 350. Additionally, femtocellsystem 350 includes electronic serial number (ESN) screening, and/orMobile Equipment Identifier (MEID) screening, to allow only designatedUEs to access the femtocell thereby restricting access to authorizedhome or small office UEs. For example, femtocell system 350 may beconfigured with an ESN and/or MEID list 354 that specifies ESNs and/orMEIDs of UEs authorized to access femtocell system 350. In theillustrative example, ESNs of “ESN 1”-“ESN 3” are included in ESN list354. Provisioning of ESN(s) and/or MEID(s) may be made as part of aninitial femtocell system 350 activation. In the illustrative example,femtocell system 350 is allocated an Internet Protocol (IP) address of“66.249.73.42”, and UE 325 is allocated a mobile services ISDN (MSISDN)number, or E.164 number, of “12145551212”.

FIG. 4A is a simplified diagrammatic representation of femtocell system350 depicted in FIG. 3 that facilitates provisioning of a femto-RAN inaccordance with an embodiment. Femtocell system 350 includes an antenna400 coupled with a BTS 410. BTS 410 may be implemented, for example, asa 1×RTT ASIC device and may comprise a non-diversity receiver featuringa built-in duplexer. In an embodiment, BTS 410 may feature only oneoperational band and may include a transmitter scan receiver and localoscillator. BTS 410 may be communicatively coupled with a BSC 420 thatprovides radio control functions, such as receiving measurements fromUEs, such as mobile phones, control of handovers to and from otherfemtocell systems, and may additionally facilitate handoff to or frommacrocells.

Femtocell system 350 includes an electronic serial number screeningfunction 430 that may facilitate approving or rejecting service for a UEby femtocell system 350. Additionally femtocell system 350 includes anInternet Operating System (IOS) and SIP Adapter (collectively referredto as IOS-SIP Adapter 440). IOS-SIP adapter 440 may invoke and manageSIP clients, such as a user agent (UA) pool comprising one or more UAs.In accordance with an embodiment, each UE 325 authorized to be servicedby femtocell system 350 may have a UA allocated therefor by femtocellsystem in a manner that facilitates transmission of communications toand from a UE over an IP backhaul. Accordingly, when an authorized UE iswithin the femtocell system 350 site range, telecommunication servicesmay be provided to the UE via the IP backhaul and femtocell system 350provisioned RAN. When the UE is moved beyond the service range offemtocell system 350, telecommunication service may then be provided tothe UE via macrocellular coverage.

To facilitate routing of calls from circuit switched call originators,femtocell system 350 may perform a DNS/ENUM registration on behalf ofUEs authorized to obtain service from femtocell system 350. In thepresent example, assume UE 325 with a MSISDN of “12145551212” has a SIPservice subscription in the domain “example.com” and has a SIP uniformresource identifier (URI) of “12145551212@example.com”. An exampleDNS/ENUM registration message generated by femtocell system 350 onbehalf of UE 325 and transmitted to DNS 372 is as follows:

$ORIGIN 2.1.2.1.5.5.5.4.1.2.1.e164.arpa.

IN NAPTR 100 10 “u” “E2U+sip” “!^.*$!sip:12145551212@example.com!”.

As is understood, the first line of the registration message comprisesthe MSISDN number of the UE converted (i.e., reversed with each numeraldelineated with a “.” character and appended with the e164.arpa domain)for DNS lookup. The second line of the registration message specifiesthe NAPTR record for the hosts that can further process the address—thedomain “example.com” (in which the UE with a URI of12145551212@example.com is registered) in the present example.

Femtocell system 350 may generate and issue a SIP registration on behalfof UE 325 authorized for service access by femtocell system 350.

FIG. 4B is a simplified diagrammatic representation of an alternativefemtocell system 450 that facilitates provisioning of a femto-RAN inaccordance with an alternative embodiment. Femtocell system 450 includesan antenna 400 coupled with a radio node (RN) 411. RN 411 may beimplemented, for example, as a 1×EV-DO ASIC device. For example, RN 411may provide a 1×EV-DO Rev. 0 air interface or a 1×EV-DO Rev. A airinterface. RN 411 may be communicatively coupled with a radio networkcontroller (RNC) 421 that provides radio control functions, such asreceiving measurements from UEs, control of handovers to and from otherfemtocell systems, and may additionally facilitate handoff to or frommacrocells. RNC 421 may also provide encryption/decryption functions,power, load, and admission control, packet scheduling, and various otherservices.

Femtocell system 450 includes an electronic serial number screeningfunction 430 that may facilitate approving or rejecting service for a UEby femtocell system 450. Additionally, femtocell system 450 includes anInternet Operating System (IOS) and SIP Adapter (collectively referredto as IOS-SIP Adapter 440). IOS-SIP adapter 440 may invoke and manageSIP clients, such as a user agent (UA) pool comprising one or more UAs.Each UE 325 authorized to be serviced by femtocell system 450 may have aUA allocated therefor by femtocell system 450 in a manner thatfacilitates transmission of communications to and from a UE over an IPbackhaul. Accordingly, when an authorized UE is within the femtocellsystem 450 site range, telecommunication services may be provided to theUE via the IP backhaul and femtocell system 450 provisioned RAN. Whenthe UE is moved beyond the service range of femtocell system 450,telecommunication service may then be provided to the UE viamacrocellular coverage. Femtocell system 450 may perform a DNS/ENUMregistration on behalf of UEs authorized to obtain service fromfemtocell system 450 and may generate and issue a SIP registration onbehalf of a UE authorized for service access by the femtocell system 450in a manner similar to that described above with reference to femtocellsystem 350.

FIG. 5 is a diagrammatic representation of an exemplary SIP registrationmessage 500 generated by femtocell system 350 on behalf of UE 325authorized for service access thereby in accordance with an embodiment.Registration message 500 may be transmitted from femtocell system 350 toan IP switch, such as SIP switch 380 that includes a SIP Registrar 382.Registrar 382 may provide the location and contact information to alocation server 384. Registration message 500 includes a REGISTER field510 that specifies the registration is being made within the domain“example.com”. Multiple contacts may be included in registration message500. In the present example, registration message 500 includes a contactfield 512 that specifies a SIP contact for UE 325. Notably, the SIPcontact field 512 for UE 325 specifies the UA registered on behalf of UEwith the URI 12145551212@exmaple.com is located at the IP address of“66.249.73.42”. That is, the SIP contact registered by femtocell system350 on behalf of UE 325 is to be addressed at the femtocell system 350address of 66.249.73.42 thereby resulting in routing of SIP signalingmessages to femtocell system 325. In turn, femtocell system 350 mayconvert SIP call set up messaging to RAN signaling, allocate an uplinkand a downlink channel for UE 325, and set up a call or data sessionthereon.

In the present example, registration message 500 includes a secondcontact field 514 that specifies a telephone URI, e.g., the MSISDN+1-214-555-1212 of UE 325. Thus, a location query for the SIP URIsip:12145551212@example.com would return two contacts. The first is theSIP URI that can be used to reach femtocell system 350, and thus UE 325thereby, and the second is the telephone URI that can be used to reachUE 325 via macrocellular coverage, i.e., via RAN 310. As is understood,the order of contacts 512-514 provides a contact preference, and themultiple contacts may be registered in separate registration messages.The depicted registration message including both the SIP contact URI andtelephone URI is exemplary only. Accordingly, in the present example, anattempt to contact UE 325 may first be made via the SIP URI12145551212@example.com. In the event that the session is notsuccessfully set up via the SIP contact, an attempt may be made to setupa session via RAN 310 using the telephone URI.

When the UE 325 moves outside the coverage area of femtocell system 350,another registration may be generated and submitted by femtocell system350 on behalf of UE 325 where the telephone URI is designated as thepreferred contact. Further, the SIP URI may be removed from theregistration when the UE 325 moves outside the coverage area offemtocell system 350 thereby avoiding any attempts to establish asession with UE 325 via femtocell system 350 when UE 325 has movedbeyond the femtocell system 350 coverage area.

To better facilitate an understanding of disclosed embodiments, considera call placed at circuit switched telephone 332 to UE 325. A gatewayreceives the call setup request, e.g., an Initial Address Message (IAM),and a query may be made with DNS 372 from which the domain “example.com”is resolved from the ENUM function. An INVITE message is thentransmitted to the example.com domain which, in turn, resolves thelocation of the called UE 325. Particularly, CSCF 320 may interrogatelocation server 384 and determine UE 325 is registered as located at theIP address 66.249.73.42. Accordingly, the INVITE message is routed toproxy server 376 which forwards the INVITE message to femtocell system350. Femtocell system 350 may then perform paging, channel allocation,and other procedures for provisioning a radio interface with UE 325 andissue SIP responses on behalf of UE 325. Thus, from a networkperspective, femtocell system 350 appears as a user agent to which thecall is directed. Further, UE 325 does not require a SIP client forreceiving the call because femtocell system 350 advantageously performssignaling and media conversion for signaling and media transmissionsover-the-air interface with 325. Thus, femtocell system 350 may appearas a conventional BTS to UE 325. A call from UE 325 to another terminal,such as circuit-switched telephone 332, a SIP client such aspacket-switched telephony device 374 a, or another device, may similarlybe facilitated by femtocell system 350.

As a second example, assume UE 325 has moved beyond the range offemtocell system 350. As noted above, femtocell system 350 may generateand transmit a registration message that excludes the SIP contact tofacilitate provisioning of telecommunication services via macrocellcoverage, e.g., via RAN 310. For instance, femtocell system 350 mayperiodically perform power measurements with UE 325, and upon the powermeasurement dropping below a particular power threshold, femtocellsystem may determine UE 325 is to be serviced by macrocellular coverage.Alternatively, a user may select macrocellular coverage via a userinterface provided on UE 325. In this instance, UE 325 may provide anindication to femtocell system 350 that telecommunication services areto be provided by RAN 310. Other scenarios may similarly result in adetermination that UE 325 is to be serviced by RAN 310. Upon such adetermination, femtocell system 350 may generate and transmit aregistration message on behalf of UE 325 to a registrar service, e.g.,CSCF 320 and SIP registrar 382. The contact information may then beupdated in location server 384 to indicate the telephone URI as thecontact of UE 325. In this scenario, consider a call placed at circuitswitched telephone 332 to UE 325. A gateway receives the call setuprequest, e.g., an Initial Address Message (IAM), and a query may be madewith DNS server 372 from which the domain “example.com” is resolved fromthe ENUM service. An INVITE message is then transmitted to theexample.com domain which resolves the location of called UE 325. In thepresent example, CSCF 320 may interrogate location server 384 anddetermine UE 325 has a preferred contact registered as a telephone URIof 2145551212. Accordingly, the INVITE message is routed to a gatewayserver, e.g., gateway server 390 which translates the INVITE message toa RAN-compliant call request signaling. The call may then be setup viaRAN 310 accordingly.

A network of femtocell systems may be deployed and connected with an IPbackhaul. In this implementation, an authorized UE may be serviced bythe femtocell network, and service may be transferred from one femtocellto another femtocell via a femtocell handoff procedure. In the eventthat the femtocell network is deployed in an area serviced by amacrocellular network, handoff routines may provide preference fortransferring a UE to a target femtocell system rather than a macrocellsite. In the event that a suitable femtocell is unavailable for handoffof a UE, the UE may be transferred to the macrocell site.

FIG. 6 is a diagrammatic representation of a network system 600featuring a femtocell network implemented in accordance with anembodiment of the invention. System 600 includes a RAN 610 that providesan over-the-air interface with UEs 625 a-625 c, e.g., a mobile terminal.RAN 610 may comprise, for example, a CDMA radio access network oranother suitable RAN. RAN 610 may comprise various BTSs 612 a-612 c andassociated BSCs 604 as well as other infrastructure as is understood.Each of BTSs 612 a-612 c provide a respective macrocell 602 a-602 c thatmay provide telecommunication service to UEs 625 a-625 c. BSC 604 iscoupled with a MSC 606 that provides cellular exchange services,mobility management, and other services within the area that it servesas is understood.

RAN 610 may interface with IMS 620 adapted to provide IP service to UEs625 a-625 c. To this end, RAN 610 may be communicatively coupled with aSGSN 614 and a GGSN 616. GGSN 616 is communicatively coupled with a PDF618 that provides authorization of media plane resources. PDF 618 may becommunicatively coupled with a CSCF 620.

CSCF 620 comprises various SIP servers or proxies that process SIPsignaling packets in IMS 620. CSCF 620 may include a P-CSCF, a S-CSCF,and an I-CSCF as is understood. HSS 640 stores user profiles thatspecify subscription-related information of authorized users,authenticates and authorizes users, and provides information about theuser's physical location. Various application servers 642 a-642 n mayhost and execute services and is interfaced with CSCF 620 via SIP.

The I-CSCF has an IP address that is published in DNS 672 thatfacilitates location of the I-CSCF by remote servers. Thus, the I-CSCFis used as a forwarding point for receipt of SIP packets within thedomain.

CSCF 620 is coupled with a BGCF 622 that comprises a SIP server thatprovides routing functionality based on telephone numbers. A MGCF 624performs call control protocol conversion between SIP and ISDN User Part(ISUP) and interfaces with a SGW 626 that itself interfaces with thesignaling plane of a circuit switched network, e.g., PSTN 630. A MGW 628interfaces with the media plane of PSTN 630 or another circuit switchednetwork. Resources of MGW 628 are controlled by MGCF 624. Fixed accessdevices, e.g., IP telephony devices 674 a-674 b, may connect with IMSnetwork via Internet 670 that is communicatively coupled with IMSnetwork 620 by way of border gateway 660. CSCF 620 may interface with aSIP switch 680, or other IP switch, that includes a Registrar 682 thatprocesses register requests and provides location and contactinformation to a location server 684.

A BSM 678 may be deployed in Internet 670 and may be adapted tocommunicate with numerous femtocell systems and femtocell networks. BSM678 may provide various operations, maintenance, and managementfunctions to femtocell systems. BSM 678 may provide service provisioningof femtocell systems, e.g., by providing configuration downloads tofemtocell systems and preloading default configuration data forfemtocell systems distributed via sales channels. BSM 678 may providevarious support and maintenance features, such as alarm and periodicstatistics reporting, automatic remote software image distribution tofemtocell systems, provide upgrades and reconfigurations, and mayprovide remote access via Internet 670 for diagnostics and customersupport.

Femtocell systems 650 a-650 c may include integrated BTS and BSC, oralternatively (or additionally) radio node (RN) and radio networkcontroller (RNC), functions and may feature additional capabilitiesavailable in the provided femtocell site coverage areas. Femtocellsystems 650 a-650 c provide an IP-accessible radio access network, areadapted for operation with IMS 620, and provide radio link controlfunctions. Femtocell systems 650 a-650 c may be communicatively coupledwith Internet 670 via any variety of backhaul technologies, such as an802.11x link, a 10/100 BaseT LAN link, a T1/E1 Span or fiber, cable settop box, DSL modem connected with a central office digital subscriberline access multiplexer, a very small aperture terminal (VSAT), oranother suitable backhaul infrastructure. In the illustrative example,femtocell systems 650 a-650 c may be coupled with an IP backhaul accessdevice 655, such as an Ethernet cable or DSL router. For instance,femtocell systems 650 a-650 c may be coupled with access node 655 viarespective 10/100BaseT twisted pair cables, Category 5 cabling, or othersuitable interconnection.

Each of femtocell systems 650 a-650 c provide a respective femtocellsite 651 a-651 c in which UEs 625 a-625 c may be providedtelecommunication services over an air interface. Femtocell systems 650a-650 c are communicatively coupled with one another via access device655. Femtocells 650 a-650 c deployed for conjunctively providing afemtocell service coverage area comprised of the collective femtocellsites 651 a-651 c are collectively referred to herein as a femtocellnetwork. In an embodiment, femtocell systems 650 a-650 c may exchangemessages with one another to facilitate handoff of a UE from onefemtocell to another, e.g., as UE 625 a moves out of the radio range ofa femtocell and into the radio range of another. In the depictedexample, the femtocell network provided by femtocell systems 650 a-650 cis at least partially overlapped by one or more macrocell sites 602a-602 c provisioned by macrocell BTSs 612 a-612 c. In such animplementation, femtocell systems 650 a-650 c may provide preference toanother femtocell for handoff of a UE thereto. In the event that anotherfemtocell is not available or is unsuitable for a handoff, the UE maythen be transferred to macrocellular coverage via a handoff to amacrocell BTS.

In an embodiment, each of femtocell system 650 a-650 c include arespective SIP adapter that supports a SIP client pool and providesconversion of call set-up functions to SIP client set-up functions.Additionally, femtocell systems 650 a-650 c include ESN and/or MEIDscreening to allow only designated UEs to access the femtocells therebyrestricting access to authorized home or small office UEs. For example,femtocell system 650 a may be configured with an ESN and/or MEID list654 a that specifies ESNs and/or MEIDs of UEs authorized to accessfemtocell system 650. In the illustrative example, ESNs of “ESN 1”-“ESN3” are included in ESN and/or MEID list 654 a. Provisioning of ESN(s)and/or MEID(s) may be made as part of an initial femtocell system 650activation. Other femtocell systems 650 b-650 c may be similarlyconfigured with an ESN and/or MEID list including ESNs and/or MEIDs ofUEs authorized to access the femtocell system network comprised offemtocell systems 650 a-650 c. In the illustrative example, femtocellsystems 650 a-650 c are allocated a respective IP address of“66.249.73.42”, “66.249.73.43”, and “66.249.73.44”.

In an embodiment, a private branch exchange (PBX) 656, e.g., an IP-PBX,may be deployed onsite at the SOHO that hosts the femtocell networkcomprising femtocell systems 650 a-650 c. In the illustrative example,PBX 656 is interconnected with access device 655. PBX 656 may providetelephone exchange services for UEs authorized to access the femtocellnetwork. In an implementation, femtocell systems 650 a-650 c inconjunction with PBX 656 facilitate abbreviated dialing, e.g., 4-digitdialing, between UEs within the femtocell network as described morefully hereinbelow. In an alternative embodiment, an IP switch, such asSIP switch 684, rather than PBX 656 may facilitate abbreviated dialing.

FIG. 7 is a diagrammatic representation of an exemplary softwareconfiguration 700 of a UE, such as UE 625 a, adapted for engaging incommunications with femtocell systems in accordance with an embodiment.In the exemplary configuration of FIG. 7, the UE is configured withaccess network-specific software entities 760, e.g., protocol and driversoftware associated with a particular access network technology, such asCDMA, GSM, UMTS, or another suitable radio access network, and isdependent on the particular cellular and femtocell access technology inwhich the UE is to be deployed. While configuration 700 depicts a UEadapted for deployment in a single access network technology type, theUE may be implemented as a multi-mode device and may accordingly includea plurality of access-specific entities in accordance with anembodiment. The particular configuration 700 is illustrative only and isprovided only to facilitate an understanding of embodiments disclosedherein.

In the illustrative example, configuration 700 includes a cellular modemdriver 702 for providing a physical interface with the access network inwhich the UE is deployed. An access-stratum 704 and a non-access stratum706 may be included in configuration 700. A cellular radio interface 708may be communicatively coupled with lower layers of configuration 700and may additionally interface with network and session managementlayers, e.g., a network stack 710. Configuration 700 may include anoperating system 714, such as Symbian, Blackberry O/S, or anotheroperating system suitable for mobile applications, and may coordinateand provide control of various components within the UE.

Configuration 700 may include a femto application 712 that facilitatesfemtocell network acquisition and handoff of a UE from a macrocellularnetwork to a femtocell system in accordance with an embodiment. In oneimplementation, a femtocell or femtocell network, such as thatcomprising femtocell systems 650 a-650 c, may be acquired by amicro-pilot assisted handoff routine or a mobile assisted handoffroutine as described more fully hereinbelow.

Configuration 700 may include a preferred roaming list (PRL) 716 thatcontains information used during the system selection and acquisitionprocess. PRL 716 indicates which bands, sub-bands and service provideridentifiers will be scanned, and the priority of the scan order. In theillustrative example, PRL 716 includes four entries 716 a-716 d thatrespectively specify four networks (illustratively designated “Femto”,“Macro 1”, “Macro 2”, and “Roam 1”). In the present example, assume“Femto” refers to the network of femtocell systems 650 a-650 c. Thefemtocell network is specified first in the prioritized list of PRLentries and thus indicates that the femtocell network is the preferredaccess network. Assume “Macro 1” refers to radio access network 610, and“Macro 2” refers to another cellular network. “Roam 1” specified by PRLentry 716 d may refer to another cellular network that may have aroaming agreement with the UE home network. As is understood, PRL 716may comprise an acquisition table that specifies a list of frequenciesassociated with each of the networks specified in the roaming list onwhich the UE may scan during search of a particular system and mayfurther specify PN offsets thereof. The acquisition table mayadditionally specify a network type of each listed network andassociated channel blocks.

In accordance with an embodiment, abbreviated dialing is supported bythe femtocell network operating in conjunction with an on-site PBX 656or, alternatively, an IP switch or other suitable entity. A user havingauthorized access to the femtocell network may dial another authorizeduser using an abbreviated code, e.g., a 4-digit code comprising the4-digit station number. On receipt of the call request, the femtocellsystem may evaluate the destination number to determine if it is anabbreviated code. If the dialed number is not an abbreviated code, thefemtocell system may direct the call request to the telecommunicationcore network for processing thereby. If the dialed number is evaluatedby the femtocell system as an abbreviated code, the femtocell system maydirect the call request to PBX 656 for call handling. In this instance,the PBX may determine if the abbreviated code is a valid code, i.e., ifit is assigned to an authorized UE. If so, PBX 656 may then determine ifthe dialed UE is currently in the femtocell network service area. In theevent the dialed UE is in the femtocell network service area, the PBXmay then complete the call setup within the femtocell network. If thePBX determines that the dialed UE is not currently in the femtocellnetwork service area, the PBX may direct the call request to thetelecommunication core network, e.g., IMS network 620, for processing ofthe call setup. Alternatively, the femtocell system may direct the callrequest to an IP switch, such as SIP switch 684, for call handling inthe event the dialed number is an abbreviated code. In this instance,the IP switch may determine if the abbreviated code is a valid code andif it is assigned to an authorized UE. If so, the IP switch may thendetermine if the dialed UE is currently in the femtocell network servicearea. In the event the dialed UE is in the femtocell network servicearea, the IP switch may then direct call setup completion within thefemtocell network. If the IP switch determines that the dialed UE is notcurrently in the femtocell network service area, the IP switch maydirect processing of the call request to the telecommunication corenetwork.

FIG. 8 is a diagrammatic representation of a PBX data structure 800 thatfacilitates abbreviated code dialing within a femtocell network inaccordance with an embodiment. In the illustrative example, the PBX datastructure is implemented as a table although other data structures maybe suitably substituted therefor.

Data structure 800 comprises a plurality of records 810 a-810 c(collectively referred to as records 810) and fields 820 a-820 c(collectively referred to as fields 820) in which authorized UEdirectory numbers and abbreviated codes therewith are stored. Datastructure 800 may be stored on a memory device of PBX 656, fetchedtherefrom by a processor of the PBX, and processed thereby.

Fields 820 a-820 c have a respective label, or identifier, thatfacilitates insertion, deletion, querying, or other data operations ormanipulations of data structure 800. In the illustrative example, fields820 a-820 c have respective labels of “Directory Number,” “AC,” and“Femto SA”.

Directory Number field 820 a stores directory numbers, e.g., an MSISDN,of UEs that are authorized to access the femtocell network. In theexamples provided herein, assume UEs 625 a-625 c are authorized toaccess the femtocell network comprising femtocell systems 650 a-650 cand further assume that UEs 625 a-625 c respectively have directorynumbers of “12145551212”-“12145551214”. AC field 820 b storesabbreviated codes, e.g., the 4-digit station number of the associatedUE. Femto SA field 820 c may store a Boolean value that indicateswhether the UE associated with a particular data structure record iscurrently located in the femtocell service area. Thus, for example, UEs625 a and 625 c having respective directory numbers of “12145551212” and“12145551214” are currently located in the femtocell service area asindicated by the True (T) value of the Femto SA field 820 c, and UE 625b having a directory number of “12145551213” is not currently located inthe femtocell service area as indicated by the False (F) value of theFemto SA field 820 b. In accordance with an embodiment, PBX 656 mayreceive call setup requests from femtocell systems 650 a-650 c thatreceive call requests having a destination number entered as anabbreviated code. The PBX may, in turn, evaluate whether the abbreviatedcode is a valid code and, if so, determine whether the dialed UE iscurrently located in the femtocell network service area. If theabbreviated code is valid and the dialed UE is within the femtocellnetwork service area, the PBX may setup the call within the femtocellnetwork. If the dialed abbreviated code is a valid code but the dialedUE is not currently in the femtocell network service area, PBX 656 maytransmit the call setup request to the IMS network 620 for processing ofthe call setup.

FIG. 9 is a flowchart 900 that depicts a femtocell call processingroutine implemented in accordance with an embodiment. The processingsteps of FIG. 9 may be implemented as computer-executable instructionsexecutable by a processing system, such as a femtocell system, inaccordance with an embodiment.

The processing routine is invoked (step 902), and a femtocell systemreceives a call setup request from a UE (step 904). The femtocell systemmay screen the call originating UE to evaluate whether the UE isauthorized to access the femtocell system (step 906). The particularimplementation of UE screening is outside the scope of the presentdisclosure. In the event that the call originating UE is not authorizedto access the femtocell system, the femtocell system may reject the callsetup (step 908), and the call processing routine cycle may then end(step 916).

Returning again to step 906, if the femtocell system determines the calloriginating UE is authorized to access the femtocell system, thefemtocell system may then evaluate the destination number to which thecall is directed to determine if the destination number is anabbreviated code (step 910), e.g., a 4-digit number. In the event thatthe destination number is not an abbreviated code, the femtocell systemmay direct the call setup request to IMS network 620 (step 912), and thecall processing routine cycle may then end according to step 916. If thedestination number is evaluated as an abbreviated code at step 910, thecall setup request may be directed from the femtocell system to thefemtocell network PBX 656 for completion of the call setup thereby (step914). In an alternative embodiment, an IP switch, such as SIP switch684, may be configured for abbreviated code call setup processing. Inthis implementation, the femtocell system directs the call setup requestto the IP switch, rather than a femtocell network PBX, at step 914. Thecall processing routine cycle may then end according to step 916.

FIG. 10 is a flowchart 1000 that depicts a PBX call processing routineimplemented in accordance with an embodiment. The processing steps ofFIG. 10 may be implemented as computer-executable instructionsexecutable by a processing system, such as IP-PBX 656 deployed in afemtocell network, in accordance with an embodiment.

The PBX call processing routine is invoked (step 1002), and a call setuprequest is received by the PBX from a femtocell system (step 1004). ThePBX may then evaluate whether the destination abbreviated code is avalid abbreviated code (step 1006). For example, the PBX may interrogatedata structure 800 with the destination abbreviated code to determine ifan entry of data suture 800 has a matching abbreviated code. If theabbreviated code is not valid, the PBX may then notify the femtocellsystem of a call failure (step 1008), and the PBX call processingroutine cycle may then end (step 1016).

Returning again to step 1006, if the destination abbreviated code isevaluated as a valid abbreviated code, the PBX may then determinewhether the UE assigned the dialed abbreviated code is currently withinthe femtocell network service area (step 1010). For example, the PBX mayevaluate the Femtocell SA field 820 c of data structure 800 allocatedfor the UE with the dialed abbreviated code to determine if the calledUE is currently within the service area of the femtocell network. If thecalled UE is not within the femtocell network service area, the PBX maythen route the call setup to the IMS network (step 1012), and the PBXcall processing routine cycle may then end according to step 1016. Ifthe PBX determines that the called UE is currently within the femtocellnetwork service area at step 1010, the PBX may then complete the callsetup within the femtocell network (step 1014), and the PBX callprocessing routine cycle may then end according to step 1016. In analternative embodiment, the femtocell network may not include an IP PBXand SIP switch 684 may be configured for abbreviated code call setupprocessing. In this implementation, the SIP switch 684 generallyperforms the processing steps, or suitable substitutions, of thosedescribed in FIG. 10. In another embodiment, the PBX functions describedabove may be incorporated into a femtocell system and the IP PBX may beexcluded from the femtocell network.

As described, a communication system featuring an IP-based femtocellsystem for provisioning communication services to a user equipment isprovided. In one implementation, abbreviated dialing is supported by thefemtocell network operating in conjunction with an on-site PBX. A userhaving authorized access to the femtocell network may dial anotherauthorized user using an abbreviated code, e.g., a 4-digit codecomprising the 4-digit station number. On receipt of the call request,the femtocell system may evaluate the destination number to determine ifit is an abbreviated code. If the dialed number is not an abbreviatedcode, the femtocell system may direct the call request to thetelecommunication core network for processing thereby. If the dialednumber is evaluated by the femtocell system as an abbreviated code, thefemtocell system may direct the call request to the PBX for callhandling. In this instance, the PBX may determine if the abbreviatedcode is a valid code, i.e., if it is assigned to an authorized UE. Ifso, the PBX may then determine if the dialed UE is currently in thefemtocell network service area. In the event the dialed UE is in thefemtocell network service area, the PBX may then complete the call setupwithin the femtocell network. If the PBX determines that the dialed UEis not currently in the femtocell network service area, the PBX maydirect the call request to the telecommunication core network forprocessing of the call setup.

The flowcharts of FIGS. 9-10 depict process serialization to facilitatean understanding of disclosed embodiments and are not necessarilyindicative of the serialization of the operations being performed. Invarious embodiments, the processing steps described in FIGS. 9-10 may beperformed in varying order, and one or more depicted steps may beperformed in parallel with other steps. Additionally, execution of someprocessing steps of FIGS. 9-10 may be excluded without departing fromembodiments disclosed herein.

The illustrative block diagrams depict process steps or blocks that mayrepresent modules, segments, or portions of code that include one ormore executable instructions for implementing specific logical functionsor steps in the process. Although the particular examples illustratespecific process steps or procedures, many alternative implementationsare possible and may be made by simple design choice. Some process stepsmay be executed in different order from the specific description hereinbased on, for example, considerations of function, purpose, conformanceto standard, legacy structure, user interface design, and the like.

Aspects of the present invention may be implemented in software,hardware, firmware, or a combination thereof. The various elements ofthe system, either individually or in combination, may be implemented asa computer program product tangibly embodied in a machine-readablestorage device for execution by a processing unit. Various steps ofembodiments of the invention may be performed by a computer processorexecuting a program tangibly embodied on a computer-readable medium toperform functions by operating on input and generating output. Thecomputer-readable medium may be, for example, a memory, a transportablemedium such as a compact disk, a floppy disk, or a diskette, such that acomputer program embodying the aspects of the present invention can beloaded onto a computer. The computer program is not limited to anyparticular embodiment, and may, for example, be implemented in anoperating system, application program, foreground or background process,driver, network stack, or any combination thereof, executing on a singleprocessor or multiple processors. Additionally, various steps ofembodiments of the invention may provide one or more data structuresgenerated, produced, received, or otherwise implemented on acomputer-readable medium, such as a memory.

Although embodiments of the present invention have been illustrated inthe accompanied drawings and described in the foregoing description, itwill be understood that the invention is not limited to the embodimentsdisclosed, but is capable of numerous rearrangements, modifications, andsubstitutions without departing from the spirit of the invention as setforth and defined by the following claims. For example, the capabilitiesof the invention can be performed fully and/or partially by one or moreof the blocks, modules, processors or memories. Also, these capabilitiesmay be performed in the current manner or in a distributed manner andon, or via, any device able to provide and/or receive information.Further, although depicted in a particular manner, various modules orblocks may be repositioned without departing from the scope of thecurrent invention. Still further, although depicted in a particularmanner, a greater or lesser number of modules and connections can beutilized with the present invention in order to accomplish the presentinvention, to provide additional known features to the presentinvention, and/or to make the present invention more efficient. Also,the information sent between various modules can be sent between themodules via at least one of a data network, the Internet, an InternetProtocol network, a wireless source, and a wired source and viaplurality of protocols.

What is claimed is:
 1. A system, comprising: a packet-switched network;an IP Multimedia subsystem communicatively coupled with thepacket-switched network; and a femtocell network communicatively coupledwith the packet-switched network, the femtocell network comprising aprivate branch exchange, wherein the femtocell network includes afemtocell that directs a call setup request from a first user equipmentintended for a second user equipment to a private branch exchangedeployed in the femtocell network if a destination number is anabbreviated code of a telephone number derived from the destinationnumber or directs the call to a core network communicatively coupledwith the femtocell network if the destination number does not comprisethe abbreviated code.
 2. The system of claim 1, wherein the femtocelldetermines the destination number comprises a four-digit abbreviatedcode.
 3. The system of claim 1, wherein the femtocell transmits thesetup request to the private branch exchange, wherein the private branchexchange associates directory numbers of authorized user equipment withabbreviated codes.
 4. The system of claim 1, wherein the private branchexchange determines that the second user equipment is located in aservice area of the femtocell network and sets up the call in thefemtocell network.
 5. The system of claim 1, wherein the private branchexchange determines that the second user equipment is not located in aservice area of the femtocell network and transmits the call setuprequest to the IP Multimedia subsystem to process the call set uprequest.